A daytime running lamp (DRL, also referred to as a daytime running light) is a lighting device mounted on the front of a vehicle (automobiles and trucks), which typically emits white light. DRLs are intended for daytime use, to increase the visibility of the vehicle in daylight. Mandated in many countries, including Canada, DRLs automatically switch on when the engine is running (e.g., when the ignition key is turned, or optionally when the vehicle is moving forward or the forward gear is engaged), and turn off when the parking lights or headlights are switched on.
Depending on prevailing regulations and vehicle equipment, the daytime running light function may be implemented by functionally specific lamps, by operating the low beam headlamps or fog lamps at full or reduced intensity, by operating the high beam headlamps at reduced intensity, or by steady-burning operation of the front turn signals at full or increased intensity (en.wikipedia.org/wiki/Daytime_running_lamp).
Various studies have shown that daytime running lights reduce daytime accidents by making vehicles more conspicuous to other road users (e.g., to drivers of other vehicles and particularly to more vulnerable road users such as pedestrians, bicyclists, and motorcyclists). The greatest benefits are found with the more severe accidents, such as head-on and intersection crashes and collisions with pedestrians and cyclists (members.optusnet.com.au/carsafety/paine_drl_nrma_racv.pdf). However, various disadvantages have been identified, including waste of energy (increased fuel consumption), glare from wet roads, and increased frequency of lamp failure (e.g., when an existing low beam, high beam, or turn signal lamp is used for the DRL function and is run down faster due to the additional usage).
Improved DRLs, which can increase the performance and effectiveness of these devices as well as the safety benefits thereof, are needed.